Prospective life cycle assessment of organic redox flow batteries

Abstract

Redox flow batteries (RFBs) are considered a promising technology for stationary energy storage. Organic redox flow batteries (OFBs) are emerging as alternatives to vanadium redox flow batteries (VFBs), since the former consist of cheap and abundant organic materials with the potential to offer lower environmental impacts. Despite numerous life cycle assessment (LCA) studies of VFBs, there is a lack of LCAs of OFBs. In this study, this gap is addressed by an LCA of an OFB and a hybrid redox flow battery (HFB) based on TEMPO electrolytes. A battery design model and a battery performance model were established to provide part of the inventory data required for the LCA. Compared to VFBs, OFBs and HFBs demonstrated superior cradle-to-gate environmental performance for acidification, human toxicity (carcinogenic), and particulate matter, but inferior performance for climate impact, freshwater ecotoxicity, and resource depletion. The primary environmental hotspots associated with battery production were electrolyte active materials, inverters, and end plates. The cradle-to-use environmental impact results showed that the OFB outperformed the VFB and HFB, primarily because the OFB's low electrolyte capacity fade rate leads to reduced electrolyte consumption during use. Sensitivity analysis indicates that future research should prioritize improvements to the electrolyte capacity fade rate. Given the early development stage of OFB and HFB technologies, there is potential to improve them further into more environmentally friendly energy storage systems.